HP-UX HB v13.00 Ch-15 - Serviceguard

HP-UX Handbook – Rev 13.00 Page 95 (of 108)
Chapter 15 Serviceguard
October 29, 2013
or/and to divide it into virtual disk volumes which are transparently presented as a physical
devices used by the operating system and different applications.
VxVM can be used in clusters that:
• are of any size, up to 16 nodes.
• require a fast cluster startup time.
• do not require shared storage group activation. (required with CFS)
• do not have all nodes cabled to all disks. (required with CFS)
• need to use software RAID mirroring or striped mirroring.
• have multiple heartbeat subnets configured.
Cluster Volume Manager
The CVM allows VxVM disk groups to be activated on many nodes at the same time, which also
gives the opportunity to choose between different modes. So it would be possible to allow read-
only access to a node while another has a read-write access.
CVM is bundled with SGeRAC and beginning with A.11.17, certain Serviceguard Storage
Management Suite (SMS) bundles that include cluster file system enablement.
CVM imposes a “Uniform Shared Storage” model. All systems must be connected to the same
disk sets for a given disk group. Any system unable to see the entire set of physical disks for a
given disk group cannot import the group. If a node loses contact with a specific disk, CVM
excludes the node from participating in the use of that disk.
CVM 3.5 supported only single heartbeat network with standby LAN card(s) and single
heartbeat network with APA and worked with SGeRAC.
Dual (multiple) heartbeat networks and single heartbeat network with standby LAN card(s) are
the minimum recommended configurations for CVM 4.1, used by SMS A.01.0x for A.11.17.
CVM 5.0 is matched to A.11.18 and SMS A.02.00.
VxFS5.0 features:
• Extent-based space management that maps files up to 1 terabyte in size
• Fast recovery from system crashes using the intent log to track recent file system
metadata updates
• Online administration that allows file systems to be extended and defragmented
while they are in use
SLVM Single Node Online volume Re-configuration
Rarely referenced in customer support cases, the SLVM Single Node Online volume Re-
configuration (SNOR) feature allows changing the configuration of an active shared volume
group in a cluster by deactivating the VG on all but one node, and on that node, changing the
volume groups activation mode to exclusive (vgchange –a e –x ..) so that LVM modifications
can occur. After modifications, the activation mode is changed back to shared-mode (vgchange
–a s –x ..).and other nodes are then allowed to start their packages that activate the VG in shared
mode